Retort apparatus and method



Sept 27, 1960 R. F. DEI-:RING ET As. 2,954,328

RETORT APPARATUS AND METHOD Filed June 19 1958 4 Sheets-Sheet l mWMQ/@ Sept- 27, 1950 R. F. DEERING :TAL 2,954,328

RETORT APPARATUS AND METHOD 4 Sheets-Sheet 2 Filed June 19, 1958 MW N N ww wm. Am

.N @NNN Sept. 27, 1960 R. F. DEERING ET AL 954,328

RETORT APPARATUS AND METHOD Filed June 19. 1958 v 4 Sheets-Sheet 3 v YZ/Z6.- .-3, 5a.;

Sept- 27, 1960 R. F. DEERING ET AL 2,954,328

RETORT APPARATUS AND METHOD Filed June 19, 1958 4 Sheets-Sheet 4 nited States Patent RETORT APPARATUS AND METHOD Roland F. Deering, Brea, and Herbert F. Wilkinson, Fullerton, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Filed June 19, 1958, Ser. No. 743,084

14 Claims. (Cl. 2072-45) lowing herein will be conducted in terms of the eduction e of shale oil and gas from oil shale.

Oil shale is -fed upwardly in sequence through a per-V forated disengaging section and a kiln section. Air orl other oxygen-containing gas enters the top and moves downwardly through the kiln section. The air is preheated by cooling the hot shale ash at the kiln top, then the air supports burningof carbonaceous residue comprising oil free shale at a lower level or zone, and then continues downward as a flue gas mixture to lower levels Where shale rock is heated and hydrocarbon oil and gases are educted therefrom. In such an upow process of oil shale, the vapor phase passes downward in direct contact with the upwardly moving raw cooler shale which condenses the hydrocarbon oil and preheats the raw shale near the bottom of the kiln. At the apparatus disengaging section liquid and gaseous products are drawn off and separated from the upwardly moving shale rock. A solids feeder situated below the kiln passes theoil shale upwardly through the disengaging and eduction kiln zones and pushes the shale ash out of the top of the unit. Carbonaceous deposits on oil-free shale after eduction periphery of the retort.

Ice Patented sept. 27, 1960 a circular retort. In center-to-periphery ash removal means, i-f it is desired to collect the ash at a limited collection area, further ash moving means is necessary to move the ash circumferentially around the entire retort to the limited collection area. Such a second ash movlng means is necessarily power driven, and this further complicates mechanical structure of a center-to-periphery ash moving means.

scraper bar construction also generally results in a longer than desired spiral path of ash across the retort to the This presents diiiiculty since excessive attrition of ash against ash results in undue production of clinker forming ash nes and/or increase in bed density resulting in increased resistance to gas flow through the bed. l

It is, therefore, an object of this invention to provide an ash removal means for an upward solidsflow retorty which retort has a broad ash bed.

`It is a further object of this invention to provide such an ash removal means in which mechanical means for circumferential ash movement relative to the retort may be minimized.

- It is also an object of the invention to provide apparatus which minimizes the average path length of ash `particles over the ash surface during the removal process, and in such manner also reduces production of ash fines resulting'from attrition of vash against ash and scraperl against ash.

'Ihe invention is carried out by providing a reciprocat- Y ying type retort ash scraper which moves substantiallyA before eduction cools and partially condenses the uct oil.

The foregoing upow process for solids fluid contacting, although superior to other processes in many respects, does present some difficulties, one of which is the removal of ash. This has heretofore been accomplished by allowing a lbuildup of ash to result in a natural removal by gravity, and it has also been accomplished by various retort center-to-periphery operative ash removal means. These methods and means of ash removal have been found to involve a number of difficulties. Natural gravity ash removal, for example, has a particular natural height and form of ash buildup which is not necessarily suitable for best process operation, especially for large kilns having broad ash beds. Center-to-periphery ash removal, While suitable for optimum shaping of an ashbed upper surface, for example, has difdiculties associated therewith such as providing convenient, low cost, land structurally strong mechanical means above the hot retort which mechanical means will not fail as a result of such extreme heat condition with factors such as high thrust v scraper operation, high solids upward flow rates and broad ash beds. vIt is also of interest to note that the center- Prod-f horizontally and with little, if any, rotary movement While travelingV across' the retort top.

The invention will be more fully understood from the following description and drawings of which:

Fig. 1 'is an elevation view in partial cross-section of a complete solids-fluid contacting apparatus showing the present invention as applied to the retorting of oil shale, and indicates at the upper end thereof the reciprocating type retort scraper apparatus employed on such a retort having a broad upper area;

Fig. 2 is a plan view in partial cross-section of the apparatus shown in Fig. 1;

Fig. 3 shows diagrammatically an alternate form ofy a 'e pivoted reciprocating scraper; Y

Fig. 4 shows diagrammatically the alternate form of Vthe reciprocating scraper of Fig. 3 driven from any end opposite to its pivot end;

Fig. 5 shows diagrammatically an alternate form of pivoted reciprocating scraper apparatus having a plurality n of blades, and which blades are driven hydraulically by engagement with scraper extensions located exterior to positions above a kiln.

Fig. 6 shows diagrammatically, a scraper assembly as I' in Figs. l and 2. adapted to a pressurized air downliow process; and

|Fig. 7 shows Ia top view of the diagrammatic, sketch in Fig. 6.

Referring now to thepdrawings, the apparatus of then present invention will be described. The apparatus c'omprises essentially four parts (see Fig. 1). First, an upper assembly 10 for directing air ow and for containing Assembly 10 is provided with n a reciprocating type ash 'scraper 11 movably mounted i ash scraping apparatus.

therein for scraping the surface of the upper solids bed 12 Within the assembly 10. The upper solids bed-12 has an air preheating vzone 15 at its outer layer .for preheatingv the air passing therethrough, and just-below'the' outer layer a burning zone 16 for the burning oflcarr bonaceous material in substantially oil-free shale withi'fT .this zone.

Centrally rotatable ash scraper apparatus having simple and practical relatively straight A second part of apparatus comprises a solids-fluid contacting 'kiln 17 having therein (Within the upwardly moving shale) at successively lower levels an eduction zone 18 in which shale oil is educted' from oil shaleby downward moving ilue gas at a suitable vtemperature obtained from the burning zone above, and the kiln 1'7 also has part of a raw shalepreheating zone '19.

A thirdV part of apparatus comprises a perforate disengaging section 20 having a lluiid disengaging zone 21' in addition to'having part of the shale preheating zone 19.

VAreciprocating shale feeder piston 22 within a feeder case, or housing 23, comprisesa fourth part of the apparatus'.

Cylinder 24 oscillates aboutl a trunnion 25. A hydraulic actuating cylinder 26 isedisposed Within cylinder 24 to reciprocate feeder piston 22. A second hydraulic cylind'er"'27"contained within feeder case23 oscillates feeder cylinder 24 between a slanted filling position tothe left (at which time feeder cylinder 24 is in a communicating llingn relationship with shale feeder hopper 28) and a vertical feeding position as depicted. Guards 80 and 81 on opposite sides of cylinder Z4 alternately close olf the bottom of the feed hopper 28 and the bottom shaleentry of the disengaging section 20, respectively. When oscillating to the lilling position shale feeder piston 422 is at its upper extremity. When at the lilling position cylinder 26 retracts shale feeder piston 22 drawing a charge of shale rock into the upper part of feed cylinder 24. Hy-

draulic cylinder 27 is then Vextended returning feederl cylinder 24 tothe vertical position shown. Then hydraulic ycylinder 26-is extended forcing shale feeder piston 22 upwardly thereby moving the charge of shale rock into disengaging apparatus section 20 and displacing hot spent shale ash from the topof kiln 17.

Hot shale ash 30 is discharged through chutes 29 through which the ash falls by gravity, during which time air, for supporting the combustion in the burning zone 16, enters through two ash discharge chutes 29 and is thereby preheated before use in the process by hot discharging ash with which the air comes in contact.

Upward solids flow moves first through the disengaging zone 21. iny which the cooled' eduction gases and shale gases and the` condensed shale oil are disengaged from the upwardly moving shale. Shale then passes isuccessively 'upward from the disengaging zone 21 to the fresh raw shale preheating zone 19 where shale is preheated andrproduct cooling and condensing also take place, then to the preheated shale eduction zone 18, the burning zone 16, andthe air or oxygen preheating zone 15, which successive zones comprise zones of the upwardly moving solids in the apparatus from the bottom to the top in the order named.

The burning zone 16 and the air or oxygen kpreheating zone 15 may be maintained at a desired elevation, for example, such zones may be maintained in the positions shown, both of which zones are located substantially above the kiln 17. Control of therate of shale feed by adjustment of the rate of reciprocation of piston 22 will operate to position zones 16 and 15 in the desired elevational location. Control of shale feed rate may be accomplished manually, or automatic control may be used. such as control meansI sensitive to temperatures at one or more points in zones 15, 16, 1S and/or 19, pressure, 'differentials from top to bottom of the shale in the kiln, or rates of idownow of iluids through the kiln, all of which are conditions which vary to some extent with or effect the elevational position of the various process zones.

The combined depth of the burning zone 16 and the air or Ioxygen preheating zone 15 is to some extent 'a functionof the diameter of kiln 17 at its top, and of the material being processed therein, including the permea-v l bility :of the; burning material mass to gaseous iluid and the natural angle of repose of its ash. For oil shale the Shale feeder housing 23 contains a vertically reciprocating feeder piston 22 within afeed cylinder '24..

ratio of the combined depth of zones 16 and 15 (that is, vthe maximum height of'material'of the process above'the kiln), to the kiln diameter is of the order of about 1:5 to 1:6. For this range of ratio, the ash of zone 15 will have approximately equal depth at its central area and at its peripheral, or outer circumferential areas.

Downward flow comprises non-oxidizing hot eduction gases produced in burning zone 16 from air, or oxygen which supports burning of carbonaceous deposits on solids therein. This gas mixture moves `throughthe preheated shale eduction Zone 18 vand then through the `fresh Shale preheatingvzone 19 -whereproduct coolingv andlcondensing take place, and thence to disengaging zone 21.

' Disengaging section '20' isprovided with a plurality of The gas product mixture from separator settler v33 isv withdrawn through line 35 under the influence of fgas` blower 36 and is directed through one or more mist separators such as the one indicated as 37. This separator 37 may comprise a cyclone separator, an oil wash such as an oil absorber, or an electrostatic percipitator, or any other suitable separator or combinations thereof for rei movingfmely divided liquid particles Vfrom a gas stream.

Any recovered liquid'in 'separator 37 is combined by means of line 38 with liquid Vin liquid kproduct line 34. The remaining gas stream is forced by gas blower 36 through gas product line 39 and directed toward any suitable use or treatment, or may be burned olf if desired.

Thegas product, for example, may contain a heatingv value of about B.t.u. per cubic foot and may'beused to dilute incoming air at ash chutes 29 to moderate the combustion temperatures and-conditions of eductionwithin the process of the apparatus. It should be understood that usual valves and other various means of control of the process are not shown herein since such means are well known to those skilled in the art.

The previous description indicates generally the upflow solids-fluid ycontacting process and apparatus. The following description of apparatus shown in Figs. 2 and 3 points out in particular the upper assembly 10 with the reciprocating type ash scraper 11 and apparatus closely associated therewith.

Upper assembly 10-comprises an outer rectangular boxlike enclosure structure 40 with the movable reciprocating type retort scraper 11 mounted therein on rails 41. Flanged. wheels `42 of scraper 11 ride on the rails 41. Rails 41 are parallel to each other and are disposed lengthwise Within the rectangular enclosure at a height to give the approximate desired height for the upper ash bed surfaceV 12. The rails 41 are higher than the retort top edge 43 and they are positioned to lie outside a location of an imaginary vertical extension ofthe top edge- `43. Rails, 41 are supported from below by respective rail girder linterior upper surfaces 44 (see Fig. 2)v which are an interior part of exterior rail girder structure 45 having vertically disposed strengthening members 46 (seel Fig. l). The rail girder structure 45 Vis supported on each end by laterali-beams 47V set on a plurality of posts I 48, which I-beams and posts also support the. enclo-V sure structure 40. Extending upward from the sides of the rail gir-.der structure 45, which are farthest from the retort edges, are parallel curtain walls 49 each provided withv horizontal slots 50. The upper portion of the box like enclosure structure 40 is preferably provided with exterior bracing members 51 to strengthen it. The bottom .of the enclosure structure 40 is attached in any suitable manner to the retort top 43. Two U-sha'ped slanted bottom areas around the retort, such as 52, each- Slantfrom positions in the vicinity and height of the-- assises ed bottom are'as 52 terminate just beyond and somewhatl below the retort upper edge 43. The ash chutes 29 receive ash '53 within from their respective slanted bottom areas 52 which are slanted to effectively convey the ash by gravity to ash chutes 29.

The scraper 11 has two ash scraping surfaces 54 and 55 which preferably are curved and slanted upward and backward from their respective lower pushing edges. Surfaces 54 and 55 are disposed lateral to the rails 41. Scraper end plates 56 and 57 provide the outer support for the axles of the flanged wheels 42 which are supported at an inward side by vertically disposed axle plates such as 78. The scraper end plates 56 and 57 are provided with respective horizontally disposed arms 58 and 59 which each pass through a different one of the slots l50, and which at their outer ends are attached to continuous chains 60 and 61, respectively (shown in broken section in Figs. 1 and 2).

A pair of chain sprockets 62 supported by mounts on the l-beams 47 and some of the posts 49 are connected by an interconnecting sprocket axle 63. The chain sprockets 62 provide connected rotatable end supports for the continuous chains 60 and 61 at positions beyond the vicinity of similar ends of rails 41.

At the opposite end of the long length of the rectangular enclosure 40 there are disposed a pair of chain sprockets 64 and connecting axle 65 for keeping the speed of each chain identical by providing rotatable connected end support for the opposite end of the continuous chains 60 and 61 beyond the vicinity of the opposite ends of rails 41.

Sprockets 64 are mechanically connectedco-linear with axle 65 on their outer sides to reversibly rotatable gear reduction units 66 and 67 which are driven by respective motive means 68 and 69. The gear reduction units and motive means assembly are supported on a platform 70 and support posts suc-h as 48 and 71 (see Fig. 1). Such a reversibly rotatable gear reduction unit may be controlled by an operator to reverse when the ash scraper 11 passes the upper edge 43 of the retort at either end of the scraper travel along the rails 41.y One of such positions of the scraper 11 when it is at its extreme left position of travel is shown in the igures.Y Automatic reversal of the rotation of sprockets 62 and 64 may, of course, be provided if desired, however, such automatic means of control is not mandatory since the scraper'll may be operated at slow enough speeds of the order of l to 25 feet per minute so that an operator is able to properly time reversal of sprocket rotation.

A preferable speed of the scraper providing gentle ash movement, for example, is about the order of 14 feet per minute. Scraper 11 pushes ash on one of the two forward pushing surfaces 54 and 55 depending on the direction of movement of the chain attached scraper across the ash bed surface 12. Thefpushing of ash spills such ash over the upper edge 43 of the retort to the slanted surfaces 52 and the ash chutes 29. Ash surface 12 is maintained substantially level at all times with movement of ash being initially started by a positive substantially uni-directional thrust over each portion of surface 12. Each ash particle is moved substantially directly across the retort without excess attrition of ash against ash and ash against scraper. Such excess attrition, if present, would result in excess production of ash nes which nes'sift down into the ash bed and cause clinkers, resultant hot spots, poor distribution of air entry and uneven burning zone level. Such factors can cause product degradation and product loss by burning. The average path length of individual ash particles' across the ash bed for the reciprocating scraper is generally less thanfor conventional ash scraper types, for example, for a centrally mounted rotatable straight blade ash scraper. scraper of practical and simple straight blade construe tion, radial ash movement from the central area of the top of the retort ash surface would be a long spiral path Idue to presence of only minor radially acting resultant force in comparison to larger tangentially directed force of such a centrally rotatable scraper.

t Centrally rotatable ash Scrapers which have a more gradual spiral provide thrust which is more nearly radial on the ash, however, contacting between ash and scraper is increased for such an arrangement. The longer rotatable scraper blades for such an arrangement' aggravates heat dissipation problems and structural strength problems in addition to having undesired excess attrition Iof scraper against ash.

Furthermore, since the supporting rails for the reciprocating type ash scraper are to the side and not directly above any portion of the retort, the reciprocating type ash scraper disclosed above provides a stronger scraper structure less subjected to continued heating. The center portion of the reciprocating type ash scraper, for example, is periodically removed, for a period of time, from the hot ash bed surface every 11/2 minutes for such a scraper moving at the rate ofv 14 feet per minute over a 2l foot diameter bed. Portions of such a reciprocating type ash scraper which are farthest from its center are located even shorter periods of time over the hot ash bed.

Provision for a broader ash bed retort reduces the frequency requirement of ash bed scraping and therefore reduces ash agitation.V This is because for similar feeder capacity below there is more surface area over which the ash may collect in a broader ash bed retort. The horizontal scraper of they present application, for example, may operate at a frequency of about five times per hour over the -ash bed, or a twelve minute period for one scraper pass. Sincel the travel time over the bed is of the order of two minutes, or less, a ten minute period is allowable for a scraper cooling dwell period at each end of scraper travel. Massive type scraper structure for hot metal strength is therefore substantially avoided by such cooling. Ash surface area and total thrust requirement are increased, but structural strength problems, cooling problems -and ash agitation problems are reduced substantially to give a practical broad hot ash surface scraper.

Alternative forms of reciprocating ash Scrapers are shown diagrammatically in Figs. 3, 4 and 5, each of which alternative forms lare driven and supported to the side of the kiln and not above it.

Fig. 3 shows a substantially straight scraper 300 pivoted Y on a vertical shaft 301 which is to the side of the kiln area4 represented by the circle 302. The scraper 300 may be reciprocated by afreciprocating drive of its vertical shaft 301 such that the non-pivotal end 303 of the scraper rides upon the arcuate rail 304.

It is also apparent from Fig. 3 that rotational nonreciprocating operation of scraper 300 about shaft 301v may provide ash scraping for more than one judiciously placed kiln, such as the kiln area represented by the circle 302.

Fig. 4 shows the straight scraper of Fig. 3 provided with an end hinge 405 on its non-pivotal end. A hinged arm 406 slidably engages with a driven carrier 407 movable along a rail 408 so that the scraper in Fig. 4 is driven from its non-pivotal end in a reciprocating manner by moving the carrier back and forth along its rail.

Fig. 5 shows a pair of substantially straight Scrapers 500a and 500b pivoted on vertical shafts 50111 and 501b, respectively, located on opposite sides of the kiln represented by the circle 502. The scrapers 500a and 500b may be reciprocated hydraulically about their shafts by respecand 500b, respectively. The Scrapers 500a andl500b may In a conventional centrally rotatable ash be timed in operation to not interfere with one another even though they partially pass over the same ash bed surface area.

It is to be under-stood that each of the scraper arrangements of Figs. 3, 4 and 5 y"may be provided with an air directing enclosure above the kiln. The scraper arrangements of Figs. 3 and 5, it may be observed, are adaptable to use with substantially air-tight enclosures by providing enclosures which are located at the pivoting shafts of these alternative forms. The scraper arrangement of Fig. 4, on the other handprequires'an enclosure having a slot through which hinged arm 406 may be operated outside of the enclosure by driven carrier 407.

A typical example of retorting operation on Colorado oil shale assaying 30 gallons/ton with the method and apparatus of thefinvention is as follows:

Raw oil shale:

Fischer assay, gaL/ton 30 Particle size, inchesV 1/2 to 3 Mineral, CO2, wt. percent 18 Crude shale oil:

Gravity, API 21 Yield, vol. percent FA. 80

Retort make gas:

Quantity, scf/minute 10,200

Shale ash above kiln, ft. 3

Avg. ash temp, at scraper, F 1,250 Retort wall temp. at upper edge, F 1,000 Retort wall temp. at 3' down from upper edge, F 500 Approx. angle of shale ash repose, 371/2 Straight scrape thrust, lbs. push 24,000 Rate oftravel of scraper, feet per minute 13.8

Freq. of scraper passes over ash bed, per

hour 5 Scraper dwell time between passes, minutes Indications in the above data show a temperature proile in which it appears that the major portion of burning takes place above the retort just below the l250 F. temperature position at the scraper. The retort wall at the upper edge is about at 500 F. which supports the foregoing conclusion as to the location of the burning Zone.

Figs. 6 and 7 show diagrammatically a uni-directional reciprocating scraper assembly like that in Figs. l and 2 incombination with a blower 601 for introducing pressurized air by way of ash chutes 629 into'the box-like enclosure structure 640.- Air enters enclosure 640 via air conduits 680 to air inlets 681 in the ash chutes. A pressurized chamber 682, around the chains 661 and end shafts, such `as 663 and 665, receives a portion of the air supplied by blower 601. via air conduits 683. Supplied air passes from chamber 682 by way of the usual slots for arms 658 and 659, through curtain walls 649=into enclosure 640. Gas product is forced fromhigher pressure upstream through outlet line 635 which is at atmospheric pressure on. the downstream side. Ash chutes 629 are maintained pressurizedby each being provided with-an ash solids chamberY suchV as 684.

Ash is'periodically let into ash solids chamber' 684. with ash inlet valve 685 open andash outlet valve'686 closed. Ash is periodically letout'of ash solids chamber '684 with ash inlet valve^685fclosed and ash outletv valve 686 open. 'The uni-directional reciprocating scraper disclosed is thereforeseen'to be conveniently adaptable to a solids -upflow retortingprocess in*7 which `eduction gas flowing downward andk counter-'current to solids flow is pressurized at the retort top, and product gas from combustion is discharged at atmospheric pressure at the retort bottom. Advantages associated with a higher than atmospheric pressurized air llow retort process are thus relatively easily obtained with the various scraping apparatus shown herein in various modified forms. The modified forms of the invention will be observed to be similarly easily adapted to such a pressurized process since ash discharge is conveniently localized at no more than two principal locations without circumferential ash moving apparatus.

The arrangement of the invention and its various modied forms shown herein provides good scraper heat conductivity from hot center to cool edges and also there is a lower proportion of metal at hot center than for other types of Scrapers. Advantages of the ash scraper disclosed in the present invention are, therefore, increased structural strength because of lessened concentrated heating in comparison to ash Scrapers previously known, provision for an ash scraper which is suitable for use on upper ash beds larger than previously known, and reduced attrition of scraper against ash due to providing a substantially straight blade across the kiln. There is also reduced attrition of ash against ash due to gen- `erally shorter average ash paths over the top of the retort than for practical centrally rotatable ash Scrapers previously known which when provided with straight blades across the retort have only slight radial thrust. Furthermore, for the type of scraper shown herein, the retort top may be one of many other shapes possible other than circular as in retorts previously known.

It is also an advantage that circumferential ash moving apparatus may be conveniently eliminated because the major portion of ash is discharged principally at one or two end positions of scraper travel from the top of a retort.

It is our desire that the invention shall not be limited except in accordance with the following claims since persons skilled in the art may devise means other than the specic means illustrated and described which is given herein only for the purpose of illustration.

We claim:

l. An apparatus for processing solids with a iluid comprising a vertically disposed kiln with a plurality of perforations inthekiln wall near the lower end of said kiln, an enclosure jacketing said perforated portion of said kiln and provided with fluid withdrawal means, a solids feed pump positioned beneath said kiln and adaptedl to discharge solids upwardly into and through said kiln, scraper means movably supported in a substantially horizontal plane above the upper end of said kiln perpendicular to the kiln axis by scraper support means extending past the open end of said kiln so as to permit said scraper means to be moved to a position above and to the side of the kiln, and means for reciprocating said scraper means in said plane across said open upper-end ofsaid kiln.

2.. The apparatus of claim l, wherein said open upper end of said kiln and said scraper'means are enclosed by a pressure tight chamber with means to supply a fluid under pressure to said chamber and meansto remove ash solids from said chamber.

3. The apparatus of claim 1 wherein Vsaid scraper means comprise a single, double faced, scraper blade which is perpendicular to and supported by two parallel rails positionedon opposite sides' of the kiln.

4. The apparatus accordingto `claim l whereinsaid scraper means comprise a plurality of doubleface'd scraper blades each pivotally supported at respective vpoints disposed substantially to the side of said kiln and so arranged about said kiln that each scraper, upon Yreciprocation, sweeps across only a portion of the upper kiln area.

5; Apparatus according to claim l in which said means for reciprocating said scraper means comprises at least one motive means, a sprocket rotatably engaged by said motive means and a continuous sprocket chain attached to said scraper means reciprocally movable by said sprocket.

6. Apparatus according to claim in which said motive means comprises a reversibly rotatable gear reduction unit and a driving motor mechanically engaged thereto, thereby providing reduced speed of said continuous sprocket chain relative to the higher speed normally provided said sprocket and sprocket chain by said driving motor.

7. The apparatus of claim 1 wherein the scraper means comprise a single double faced scraper blade which is pivotally supported near one end at a point substantially to the side of the kiln and is movably supported at its other end.

8. The apparatus of claim 7 wherein a plurality of kilns are clustered about said pivotal support and said scraper blade is provided with means to rotate said blade about its pivotal point and thereby sweep said blade across the top of each of said kilns.

9. Apparatus according to claim 7 in which said means for reciprocating said blade comprises motive means mechanically engaging therewith at said pivotal position.

10. Apparatus according to claim 7 in which said means for reciprocating said blade comprises motive means mechanically engaging therewith on the end along the arcuate path of said blade farthest removed from said pivotal position on an opposite side of said kiln.

11. The method of pumping solids up through a kiln, providing a gaseous fluid downow through said solids by establishing a pressurized zone of said gaseous fluid at greater than atmospheric pressure above said kiln, maintaining processing zones comprising both a lower elevation burning zone for said solids and a higher elevation gaseous uid preheating zone of burned solids substantially above said kiln, removing burned solids from the upper surface of said preheating zone by substantially horizontal reciprocal scraping, supporting scraping means exterior to the circumference of said kiln,

maintaining said scraping means out of contact with said upper surface a period of about ve of the time intervals of hot ash surface contact time in each halfcycle of reciprocation, and discharging gaseous iluid at the bottom of said kiln at about atmospheric pressure.

132. In a method for continuously processing solids wherein said solids are passed upwardly as a bed of solids successively through a solids feeding zone, a Huid withdrawal zone, a solids processing zone, a combustion zone, and an upper ash removal zone, and a combustion supporting gas is passed downwardly through the ash removal zone into the combustion zone, from which zone combustion gases are passed downwardly through said processing zone and combined educted uids and combustion gases are removed in said fluid withdrawal zone, the improved method of removing ash from said ash removal zone comprising: scraping said ash solids from the upper bed surface by periodically passing a substantially horizontal scraper across said upper bed surface and maintaining said scraper relatively cool by supporting said scraper out of contact with the hot ash solids during the non-operative portion of the scraping cycle.

13. The method of claim 12 in which the combustion supporting gas is air, the solids processed are shale, and the non-operative portion of the scraping cycle comprises to 90 percent of the processing time.

14. The method of claim 12 in which said rising mass of solids is permitted to rise substantially above the upper edge of the containing vessel and the combustion gas and solids flow rates are controlled to maintain a substantial portion of the combustion zone in the portion of said rising bed of solids which is disposed above the-` upper edge of the containing vessel.

References Cited in the tile of this patent UNITED STATES PATENTS 2,119,937 Banfield June 7, 1938 2,501,153 Berg Mar. 21, 1950 2,640,014 Berg May 26, 1953 2,640,019 Berg May 26, 1953 

11. THE METHOD OF PUMPING SOLIDS UP THROUGH A KILN, PROVIDING A GASEOUS FLUID DOWNFLOW THROUGH SAID SOLIDS BY ESTABLISHING A PRESSURIZED ZONE OF SAID GASEOUS FLUID AT GREATER THAN ATMOSPHERIC PRESSURE ABOVE SAID KILN MAINTAINING PROCESSING ZONES COMPRISING BOTH A LOWER ELEVATION BURNING ZONE FOR SAID SOLIDS AND A HIGHER ELEVATION GASEOUS FLUID PREHEATING ZONE OF BURNED SOLIDS SUBSTANTIALLY ABOVE SAID KILN, REMOVING BURNED SOLIDS FROM THE UPPER SURFACE OF SAID PREHEATING ZONE BY SUBSTANTIALLY HORIZONTAL RECIPROCAL SCRAPING, SUPPORTING SCRAPING MEANS EXTERIOR TO THE CIRCUMFERENCE OF SAID KILN, MAINTAINING SAID SCRAPING MEANS OUT OF CONTACT WITH SAID UPPER SURFACE A PERIOD OF ABOUT FIVE OF THE TIME INTERVALS OF HOT ASH SURFACE CONTACT TIME IN EACH HALFCYCLE OF RECIPROCATION, AND DISCHARGING GASEOUS FLUID AT THE BOTTOM OF SAID KILN AT ABOUT ATMOSPHERIC PRESSURE. 